Internal combustion engines may utilize a particulate filter in the exhaust to reduce the amount of particulate matter, such as soot, in emitted exhaust gas. The particulate filter traps particulate matter on a porous substrate through (or over) which the exhaust gasses flow. Once a particulate filter reaches its particulate load capacity, back pressure to the engine may increase, decreasing fuel economy. Further, excess particulates may be released to the atmosphere, increasing emissions. In order to remove the particulate matter accumulated on the filter, the particulate matter may be burned off of the filter via an active regeneration process. The regeneration process may be initiated via high temperature of the exhaust gas. The temperature of the exhaust may be high enough to commence and sustain regeneration responsive to the engine operating under relatively high engine loads. If the engine operates under lower engine loads, the exhaust temperature may not be high enough to commence or sustain regeneration, so the engine operation may be altered to increase exhaust heat and thus raise exhaust temperature sufficient for regeneration. However, the excess heat is frequently provided by combusting fuel in the exhaust without creating useful power for the engine, thereby decreasing fuel economy.
Furthermore, the active regeneration process may be relatively hard to control and, if uncontrolled, risks producing heat that can damage the filter and/or other components in the exhaust. For example, the regeneration process is an exothermic reaction that produces heat, which can increase the temperature in the exhaust, speeding up the exothermic reaction and generating additional heat in a process referred to as thermal runaway. As the vehicle system travels along a route for a trip, various engine operating conditions of the vehicle system can negatively affect the control of the active regeneration process, increasing the risk of thermal runaway. For example, if an active regeneration event occurs while the engine operates at a relatively low engine load, such as when idling, the flow rate of the exhaust may not be sufficiently high to dissipate the heat produced as the particulates burn, potentially producing a thermal runaway.